Display device and method of driving the same

Abstract

In a display device, a capacitance forming electrode is provided such that an additional capacitance is formed between the pixel electrode in pixel formation portion and the capacitance forming electrode, and the capacitance value of the additional capacitance is set equal to the capacitance value of the gate-drain capacitance. After the scanning signal being applied to the scanning signal electrode fall, a capacitance forming electrode driver raises the capacitance forming electrode drive signal being applied to the capacitance forming electrode that corresponds to the scanning signal electrodes.

1 . An active-matrix display device having a plurality of video signal electrodes, a plurality of scanning signal electrodes crossing the plurality of video signal electrodes, and a plurality of pixel formation portions arranged in a matrix so as to correspond to their respective intersections of the plurality of video signal electrodes and the plurality of scanning signal electrodes, the device comprising:
 a plurality of capacitance forming electrodes crossing the plurality of video signal electrodes;   a video signal electrode drive portion for applying video signals to the plurality of video signal electrodes, the signals representing an image to be displayed;   a scanning signal electrode drive portion for selectively driving the plurality of scanning signal electrodes by applying scanning signals to the plurality of scanning signal electrodes; and   a capacitance forming electrode drive portion for driving the plurality of capacitance forming electrodes, wherein,   each of the plurality of capacitance forming electrodes is provided so as to correspond to at least one of the plurality of scanning signal electrodes,   each of the pixel formation portions includes:
 a switching element to be brought into ON state when a scanning signal being applied to a corresponding scanning signal electrode is at a first level and OFF state when the scanning signal is at a second level, the corresponding scanning signal electrode being a scanning signal electrode passing through the intersection that corresponds to the switching element; 
 a pixel electrode disposed so as to have a first capacitance formed between the corresponding scanning signal electrode and the pixel electrode and connected via the switching element to a video signal electrode passing through the corresponding intersection; and 
 a second capacitance formed by the capacitance forming electrode corresponding to the corresponding scanning signal electrode and the pixel electrode, and 
   after the scanning signals being applied to the scanning signal electrodes change from the first level to the second level, the capacitance forming electrode drive portion changes voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes, in an opposite direction to the scanning signals changing from the first level to the second level.   
     
     
         2 . The display device according to  claim 1 , wherein,
 the capacitance value of the second capacitance is set equal to the capacitance value of the first capacitance, and   after scanning signals being applied to the scanning signal electrodes change from the first level to the second level, the capacitance forming electrode drive portion changes the voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes, from the second level to the first level.   
     
     
         3 . The display device according to  claim 1 , wherein,
 the capacitance value of the second capacitance is set greater than the capacitance value of the first capacitance, and   the capacitance forming electrode drive portion drives the capacitance forming electrodes such that the amplitudes of the voltages being applied to the capacitance forming electrodes are narrower than those of the scanning signals.   
     
     
         4 . The display device according to  claim 1 , wherein,
 the capacitance value of the second capacitance is set smaller than the capacitance value of the first capacitance, and   the capacitance forming electrode drive portion drives the capacitance forming electrodes such that the amplitudes of the voltages being applied to the capacitance forming electrodes are wider than those of the scanning signals.   
     
     
         5 . The display device according to  claim 1 , wherein,
 the capacitance value of the second capacitance is set to M times as great as the capacitance value of the first capacitance (where M is a positive number), and   the capacitance forming electrode drive portion drives the capacitance forming electrodes such that the amplitudes of the voltages being applied to the capacitance forming electrodes are set to 1/M of the amplitudes of the scanning signals.   
     
     
         6 . The display device according to  claim 1 , wherein each of the pixel formation portions consists of a first sub-pixel formation portion and a second sub-pixel formation portion, each including the switching element, the pixel electrode, and the second capacitance. 
     
     
         7 . The display device according to  claim 6 , further comprising a plurality of second video signal electrodes the number of which is equal to the number of the plurality of video signal electrodes, wherein,
 the video signal electrode drive portion further applies the video signals to the plurality of second video signal electrodes,   the pixel electrode included in the first sub-pixel formation portion is connected to the video signal electrode via the switching element, and   the pixel electrode included in the second sub-pixel formation portion is connected to the second video signal electrode via the switching element.   
     
     
         8 . The display device according to  claim 6 , further comprising a plurality of second video signal electrodes the number of which is equal to the number of plurality of scanning signal electrodes, wherein,
 the scanning signal electrode drive portion further applies the scanning signals to the plurality of second scanning signal electrodes, thereby selectively driving the plurality of scanning signal electrodes and the plurality of second scanning signal electrodes such that the scanning signal electrodes and the second scanning signal electrodes are alternately selected, and   in the second sub-pixel formation portion,
 the switching element is brought into ON state when a scanning signal not being applied to the corresponding scanning signal electrode but instead to a corresponding second scanning signal electrode is at a first level and OFF state when the scanning signal is at a second level, the corresponding second scanning signal electrode being a second scanning signal electrode passing through the intersection that corresponds to the switching element, 
 the pixel electrode is disposed so as to have the first capacitance formed between the corresponding second scanning signal electrode, in place of the corresponding scanning signal electrode, and the pixel electrode, and 
 after both the scanning signals being applied to the scanning signal electrodes that correspond to the capacitance forming electrodes and the scanning signals being applied to the second scanning signal electrodes that correspond to the capacitance forming electrodes completely change from the first level to the second level, the capacitance forming electrode drive portion changes the voltages being applied to the capacitance forming electrodes, in an opposite direction to both of the scanning signals changing from the first level to the second level. 
   
     
     
         9 . The display device according to  claim 6 , wherein,
 the pixel electrode included in each of the pixel formation portions is disposed so as to have a third capacitance formed between an electrode other than the corresponding scanning signal electrode and the pixel electrode, and
 the third capacitance is different in capacitance value between the first sub-pixel formation portion and the second sub-pixel formation portion. 
   
     
     
         10 . The display device according to  claim 1 , wherein,
 the capacitance forming electrode drive portion applies voltages to the plurality of capacitance forming electrodes such that a voltage of the same level is provided to each group of n capacitance forming electrodes which are arranged in series in an extending direction of the video signal electrodes (where n is a natural number of 2 or more), and   after all of the scanning signals being applied to the scanning signal electrodes that correspond to the n capacitance forming electrodes, to which the voltage of the same level is applied, completely change from the first level to the second level, the capacitance forming electrode drive portion changes the voltage being applied to the n capacitance forming electrodes, in an opposite direction to all of the scanning signals changing from the first level to the second level.   
     
     
         11 . The display device according to  claim 10 , wherein,
 one trunk electrode is provided per n capacitance forming electrodes in a region outside an area where the image is displayed, and   each trunk electrode is connected to the n capacitance forming electrodes arranged in series in the extending direction of the video signal electrodes and is also connected to the capacitance forming electrode drive portion.   
     
     
         12 . The display device according to  claim 1 , wherein,
 each of the plurality of capacitance forming electrodes is provided so as to correspond to two scanning signal electrodes out of the plurality of scanning signal electrodes, and is arranged between two pixel formation portions which are arranged in series in the extending direction of the video signal electrodes and correspond to the two scanning signal electrodes, the two scanning signal electrodes being arranged in series in the extending direction of the video signal electrodes, and   after all of the scanning signals being applied to the two scanning signal electrodes corresponding to the capacitance forming electrodes completely change from the first level to the second level, the capacitance forming electrode drive portion changes the voltages being applied to the capacitance forming electrodes, in an opposite direction to all of the scanning signals changing from the first level to the second level.   
     
     
         13 . The display device according to  claim 1 , wherein immediately before the scanning signals being applied to the scanning signal electrodes change from the second level to the first level or while the scanning signals are maintained at the first level, the capacitance forming electrode drive portion changes the voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes, in an opposite direction to the scanning signals changing from the second level to the first level. 
     
     
         14 . The display device according to  claim 1 , wherein within one horizontal scanning period from the change of the scanning signals being applied to the scanning signal electrodes from the first level to the second level, the capacitance forming electrode drive portion changes the voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes, in an opposite direction to the scanning signals changing from the first level to the second level. 
     
     
         15 . A method for driving an active-matrix display device having a plurality of video signal electrodes, a plurality of scanning signal electrodes crossing the video signal electrodes, and a plurality of pixel formation portions arranged in a matrix so as to correspond to their respective intersections of the plurality of video signal electrodes and the plurality of scanning signal electrodes, the method comprising:
 a video signal electrode drive step for applying video signals to the plurality of video signal electrodes, the signals representing an image to be displayed;   a scanning signal electrode drive step for selectively driving the plurality of scanning signal electrodes by applying scanning signals to the plurality of scanning signal electrodes; and   a capacitance forming electrode drive step for driving a plurality of capacitance forming electrodes provided so as to cross the plurality of video signal electrodes, wherein,   each of the plurality of capacitance forming electrodes is provided so as to correspond to at least one of the plurality of scanning signal electrodes,   each of the pixel formation portions includes:
 a switching element to be brought into ON state when a scanning signal being applied to a corresponding scanning signal electrode is at a first level and OFF state when the scanning signal is at a second level, the corresponding scanning signal electrode being a scanning signal electrode passing through the intersection that corresponds to the switching element; 
 a pixel electrode disposed so as to have a first capacitance formed between the corresponding scanning signal electrode and the pixel electrode and connected via the switching element to a video signal electrode passing through the corresponding intersection; and 
 a second capacitance formed by the capacitance forming electrode corresponding to the corresponding scanning signal electrode and the pixel electrode, and 
   in the capacitance forming electrode drive step, after the scanning signals being applied to the scanning signal electrodes change from the first level to the second level, voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes change in an opposite direction to the scanning signals changing from the first level to the second level.   
     
     
         16 . The drive method according to  claim 15 , wherein,
 the capacitance value of the second capacitance is set to M times as great as the capacitance value of the first capacitance (where M is a positive number), and   in the capacitance forming electrode drive step, the capacitance forming electrodes are driven such that the amplitudes of the voltages being applied to the capacitance forming electrodes are set to 1/M of the amplitudes of the scanning signals.   
     
     
         17 . The drive method according to  claim 15 , wherein,
 in the capacitance forming electrode drive step,
 voltages are applied to the plurality of capacitance forming electrodes such that a voltage of the same level is provided to each group of n capacitance forming electrodes which are arranged in series in an extending direction of the video signal electrodes (where n is a natural number of 2 or more), and 
 after all of the scanning signals being applied to the scanning signal electrodes that correspond to the n capacitance forming electrodes, to which the voltage of the same level is applied, completely change from the first level to the second level, the voltage being applied to the n capacitance forming electrodes changes in an opposite direction to all of the scanning signals changing from the first level to the second level. 
   
     
     
         18 . The drive method according to  claim 15 , wherein in the capacitance forming electrode drive step, immediately before the scanning signals being applied to the scanning signal electrodes change from the second level to the first level or while the scanning signals are maintained at the first level, the voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes change in an opposite direction to the scanning signals changing from the second level to the first level. 
     
     
         19 . The drive method according to  claim 15 , wherein in the capacitance forming electrode drive step, within one horizontal scanning period from the change of the scanning signals being applied to the scanning signal electrodes from the first level to the second level, the voltages being applied to the capacitance forming electrodes that correspond to the scanning signal electrodes change in an opposite direction to the scanning signals changing from the first level to the second level.